New Evidence Suggests Life on Earth Emerged Through Two Independent Origins
According to researchers at Heinrich Heine University Düsseldorf, free-living cells likely emerged twice on early Earth — once along the bacterial line, once along the archaeal line.
The team reports in Science Advances that the enzymes driving core metabolism split cleanly across the bacterial-archaeal divide roughly 4 billion years ago, even as the underlying chemistry stayed shared.
Enzymes split, chemistry didn't
The researchers catalogued all 420 reactions cells use to manufacture amino acids, RNA bases, and vitamins from inputs like hydrogen, ammonia, and CO₂. Those reactions are strikingly conserved across all known life. The enzymes catalyzing them are not.
Lead author Natalia Mrnjavac and senior author William Martin found that LUCA — the last universal common ancestor — likely possessed enzymes for only about half of the 420 reactions. The remainder were driven by metals naturally present in hydrothermal vents.
If the earliest metabolism leaned that heavily on environmental catalysts, the transition to fully enzymatic life was not a single shared inheritance. It happened twice, in parallel, in two lineages that then diverged for good.
Metal chemistry fills the gaps
The team validated the point with inorganic chemistry. Harun Tüysüz of the Max-Planck-Institut für Kohlenforschung and Joseph Moran of the University of Ottawa showed that metals in vent environments can substitute for a large share of the enzymes modern cells rely on. As Moran put it, the picture emerging is "a hybrid of enzymatic and metal catalysts."
The result reframes a 4-billion-year-old question. Instead of one origin event followed by divergence, the data point to two independent starts in roughly the same geochemical setting.
What to watch next
The implications extend in two directions. Synthetic biology efforts aiming to reconstruct primitive metabolism now have a tighter target: the ~210 reactions LUCA could already run enzymatically, mapped against the steps metals can still substitute for. That narrows the engineering search space for minimal cell-like systems.
It also sharpens astrobiology. If metals can substitute for enzymes in core metabolic reactions, then molecules associated with life on Earth could in principle form without biology. Researchers can now narrow which core-metabolism products genuinely require enzymatic catalysis to flag as truly biological.
For investors tracking where origins-of-life research translates into commercial pipelines, stock analysis tools can help surface companies operating at the intersection of primitive-metabolism chemistry and applied bioengineering.